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Abstract:

The instant application describes a red phosphor material including
Y(Px, V1-x)O4:Eu, wherein a value of x is equal to or
greater than 0.3 and equal to or less than 0.8.

Claims:

1. A red phosphor material including Y(Px, V1-x)O4:Eu,
wherein a value of x is equal to or greater than 0.3 and equal to or less
than 0.8.

2. The red phosphor material of claim 1, wherein the value of x is equal
to or greater than 0.3 and equal to or less than 0.6.

3. The red phosphor material of claim 1, wherein the value of x is equal
to or greater than 0.6 and equal to or less than 0.8.

4. The red phosphor material of any one of claims 1 to 3, wherein: a
surface of the Y(Px, V1-x)O4:Eu is coated with at least
one metal oxide selected from the group consisting of magnesium oxide,
zinc oxide, and silicon dioxide, and a weight % concentration of the
metal oxide with respect to the Y(Px, V1-x)O4:Eu is
greater than 0 wt % and less than 5 wt %.

5. A plasma display panel including a red phosphor layer, wherein the red
phosphor layer is formed of the red phosphor material of claim 1.

6. A plasma display panel including a red phosphor layer, wherein the red
phosphor layer is formed of the red phosphor material of any one of
claims 2 and 3.

7. A plasma display panel including a red phosphor layer, wherein the red
phosphor layer is formed of the red phosphor material of claim 4.

Description:

TECHNICAL FIELD

[0001] The instant application relates to a red phosphor material and a
plasma display panel.

BACKGROUND

[0002] In recent years, a plasma display panel (hereinafter, referred to
as a PDP) has been applied to a three-dimensional (3-D) image display
apparatus which is combined with liquid crystal shutter glasses, and the
like.

[0003] In order to suppress occurrence of crosstalk in which an image is
seen in double from a response time of the liquid crystal shutter glasses
in a three-dimensional image display apparatus, the afterglow time of the
phosphor material should equal to or less than 4.0 msec. Here, the
afterglow time may refer to the time until emission luminance of the
phosphor material is attenuated to 1/10.

SUMMARY

[0004] In one general aspect, the instant application describes a red
phosphor material including Y(Px, V1-x)O4:Eu, wherein a
value of x is equal to or greater than 0.3 and equal to or less than 0.8.

[0005] The above general aspect may include one or more of the following
features. For example, the value of x may be equal to or greater than 0.3
and equal to or less than 0.6. Alternatively, the value of x may be equal
to or greater than 0.6 and equal to or less than 0.8. A surface of
Y(Px, V1-x)O4:Eu may be coated with at least one metal
oxide selected from the group consisting of magnesium oxide, zinc oxide,
and silicon dioxide, and a weight % concentration of the metal oxide with
respect to Y(Px, V1-x)O4:Eu may be greater than 0 wt % and
less than 5 wt %.

[0006] In another general aspect, the instant application describes a
plasma display panel including a red phosphor layer, where the red
phosphor layer is formed of red phosphor material including Y(Px,
V1-x)O4:Eu, where a value of x is equal to or greater than 0.3
and equal to or less than 0.8.

[0007] In another general aspect, the instant application describes a
plasma display panel including a red phosphor layer, where the red
phosphor layer is formed of red phosphor material including Y(Px,
V1-x)O4:Eu, where a value of x is equal to or greater than 0.3
and equal to or less than 0.6 or the value of x is equal to or greater
than 0.6 and equal to or less than 0.8.

[0008] In another general aspect, the instant application describes a
plasma display panel including a red phosphor layer, where the red
phosphor layer is formed of red phosphor material including Y(Px,
V1-x)O4:Eu, where a value of x is equal to or greater than 0.3
and equal to or less than 0.8. A surface of Y(Px,
V1-x)O4:Eu is coated with at least one metal oxide selected
from the group consisting of magnesium oxide, zinc oxide, and silicon
dioxide, and a weight % concentration of the metal oxide with respect to
Y(Px, V1-x)O4:Eu is greater than 0 wt % and less than 5 wt
%.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a partial cross-sectional perspective view showing a
configuration of PDP of the instant application;

[0010]FIG. 2 is a schematic view showing a configuration of a plasma
display apparatus of the instant application;

[0011]FIG. 3 is a schematic cross-sectional view showing a configuration
of a rear plate of a PDP;

[0012]FIG. 4 is a view showing the relationship between a value of x of
YPV and an afterglow time of a plasma display apparatus;

[0013] FIG. 5 is a view showing the relationship between powder luminance
and a process maintenance rate with respect to a value of x of YPV;

[0014] FIG. 6 is a view showing the relationship between a value of x of
YPV and panel luminance;

[0015]FIG. 7 is a view showing the relationship between a coated amount
of MgO of YPV and panel luminance;

[0016]FIG. 8 is a view showing the relationship between a coated amount
of ZnO of YPV and panel luminance; and

[0017]FIG. 9 is a view showing the relationship between relative
luminance and a luminance degradation rate with respect to a coated
amount of SiO2 of YPV.

DETAILED DESCRIPTION

[0018] Hereinafter, exemplary implementations will be described with
reference to drawings.

[0022] Front plate 20 and rear plate 30 are disposed to face each other so
that display electrode pairs 24 and address electrodes 32 cross each
other with a minute discharge space held therebetween. An outer
peripheral portion of front plate 20 and rear plate 30 is sealed by a
sealing member such as a glass frit, and the like. In the discharge
space, a mixed gas of, for example, neon (Ne), xenon (Xe), and the like
is sealed at a pressure of 55 kPa to 89 kPa as a discharge gas. The
discharge space is partitioned into a plurality of sections by partition
34, so that discharge cell 36 is formed in a portion where display
electrode pairs 24 and address electrodes 32 cross each other.

[0023] When a discharge voltage is applied between the above described
electrodes, discharge occurs within discharge cell 36. A phosphor
included in each of red phosphor layer 35R, green phosphor layer 35G, and
blue phosphor layer 35B is exited by ultraviolet rays generated by
discharge to thereby emit light. Due to this, a color image is displayed
on PDP 10. Further, a structure of PDP 10 is not limited to the described
above. For example, a structure of partition 34 may be a structure
including a partition formed in a parallel cross shape.

[0025] Next, an operation of discharge in PDP 10 will be described. First,
a predetermined voltage is applied to scanning electrode 22 and address
electrode 32 each corresponding to discharge cell 36 to be turned on.
Then, address discharge occurs between scanning electrode 22 and address
electrode 32. Due to this, wall charge is formed on discharge cell 36
corresponding to display data. Thereafter, a sustain discharge voltage is
applied between sustaining electrode 23 and scanning electrode 22. Then,
sustain discharge occurs in discharge cell 36 in which the wall charge is
formed, and ultraviolet rays are generated. The phosphor of red phosphor
layer 35R, green phosphor layer 35G, and blue phosphor layer 35B is
excited by the ultraviolet rays. The excited phosphor is emitted, so that
discharge cell 36 is turned on. An image is displayed by a combination
each color of discharge cell 36 being turned on and turned off.

[0026] 2. Manufacturing Method of Plasma Display Panel

[0027] Next, a manufacturing method of PDP 10 according to the first
implementation will be described. First, a manufacturing method of front
plate 20 will be described. On front glass substrate 21, display
electrode pairs 24 composed of scanning electrodes 22 and sustaining
electrodes 23 are formed. In this instance, a black stripe may be formed
between scanning electrode 22 and sustaining electrode 23.

[0028] Scanning electrode 22 and sustaining electrode 23 include a
transparent electrode such as ITO and a bus electrode containing Ag
formed on the transparent electrode, a glass frit, and the like. An ITO
thin film is formed on front glass substrate 21 by a sputtering method,
and the transparent electrode is formed in a predetermined pattern by a
lithography method. In addition, the bus electrode of a predetermined
pattern is formed by the lithography method. The black stripe is formed
of a material containing a black pigment. Dielectric layer 25 is formed
so as to cover scanning electrode 22 and sustaining electrode 23 by a die
coating method. Protective layer 26 is formed on dielectric layer 25 by a
vacuum deposition method. Next, a manufacturing method of rear plate 30
will be described.

[0029]FIG. 3 is a schematic cross-sectional view showing a configuration
of rear plate 30 of PDP 10 according to the first implementation. On rear
glass substrate 31, a silver paste for electrodes is screen printed. The
paste is baked, so that a plurality of address electrodes 32 is formed in
a stripe shape. In order to cover address electrode 32, a paste
containing a glass material is coated in a die coating method or a screen
printing method. The paste is baked, so that foundation dielectric layer
33 is formed.

[0030] Partition 34 is formed on foundation dielectric layer 33. As a
method of forming partition 34, a method in which the paste containing
the glass material is repeatedly coated and baked in a strip shape by the
screen printing method while sandwiching address electrode 32 is used. In
addition, a method in which the paste is coated and patterned on
foundation dielectric layer 33 by coating address electrode 32 to thereby
be baked is also used.

[0031] The discharge space is partitioned by partition 34, so that
discharge cell 36 is formed. A gap of partition 34 is set as being 130
μm to 240 μm, for example, in a full HD television of 42 to 50
inches or an HD television. On a groove between adjacent two partitions
34, the paste containing particles of the phosphor materials emitting
light in each color is coated by the screen printing method, an ink jet
method, or the like. The paste is baked, so that red phosphor layer 35R,
green phosphor layer 35G, and blue phosphor layer 35B are formed. In
addition, the phosphor materials used in each of red phosphor layer 35R,
green phosphor layer 35G, and blue phosphor layer 35B will be described
later.

[0032] The rear plate 30 and the front plate 20 manufactured as above are
sealed. In this instance, rear plate 30 and front plate 20 are
superimposed so that display electrode pairs 24 and address electrode 32
are perpendicular to each other. A sealing glass is coated on an outer
peripheral portion of rear plate 30 and front plate 20. The sealing glass
seals rear plate 30 and front plate 20. Thereafter, a mixed gas of neon
(Ne), xenon (Xe), and the like is sealed at a pressure of 55 kPa to 80
kPa after the discharge space is exhausted to a high vacuum.

[0033] In this way, PDP 10 according to the first implementation is
manufactured. The manufactured PDP 10 is connected to driving circuit 40.
In addition, a plasma display apparatus is assembled into a case, and the
like to thereby be prepared.

[0034] In this manner, PDP 10 according to the first implementation is
applied to a three-dimensional image display apparatus.

[0035] 3. Overview of Phosphor Material

[0036] Next, the phosphor material of each color used in PDP 10 will be
described. The phosphor material may be prepared using a solid phase
reaction method, a liquid phase method, or a liquid spraying method. The
solid phase reaction method is a method in which the phosphor material is
prepared by baking oxide or carboxide raw materials and flux. The liquid
phase method is a method in which the phosphor material is prepared in a
manner such that organic metal salts and nitrate are hydrolyzed in an
aqueous solution, and a precursor of the phosphor material that is
precipitated to be generated by adding alkali and the like is subjected
to heat treatment, if necessary. The liquid spraying method is a method
in which the phosphor material is prepared by spraying, into a heated
furnace, an aqueous solution containing a raw material of the phosphor
material. In the first implementation, the phosphor material is
manufactured by the solid phase reaction method.

[0038] In the first implementation, for example, BaMgAl10O17:Eu
having a short afterglow time is used as the blue phosphor material used
in the blue phosphor layer 35B. BaMgAl10O17:Eu is prepared by
the following method. Barium carbonate (BaCO3), magnesium carbonate
(MgCO3), aluminum oxide (Al2O3), and europium oxide
(Eu2O3) are mixed to match a combination of a desired phosphor
material. The mixture is baked at 800° C. to 1,200° C. in
the air. Thereafter, the mixture is baked at 1,200° C. to
1,400° C. in a mixed gas atmosphere containing hydrogen and
nitrogen. Accordingly, the blue phosphor material is prepared.

[0039] 3-2. Green Phosphor Material and Manufacturing Method of the Same

[0040] In the first implementation, as the green phosphor used in the
green phosphor layer 35G, for example, Zn2SiO4:Mn is used.
Zn2SiO4:Mn is prepared in the following method. Silicon dioxide
(SiO2), manganese compound such as manganese dioxide (MnO2),
and zinc oxide (ZnO) are mixed to match a combination of a desired
phosphor material. The mixture is baked at least once at 1,100° C.
to 1,300° C. in the air. Accordingly, the green phosphor material
is prepared. Other than this, YAl3(BO4)3:Tb,
Y3Al5O12:Ce, and the like may be used.

[0041] 3-3. Red Phosphor Material and Manufacturing Method of the Same

[0042] The red phosphor material according to the first implementation is
Y(Px, V1-x)O4:Eu (hereinafter, referred to as YPV). The
phosphorous element (P) and vanadium element (V) which are present in a
crystal lattice of YPV may have different abundance ratios by a value of
x. Here, the value of x is a value of the phosphorous element (P) with
respect to a sum of the phosphorous element (P) and the vanadium element
(V). The value of x is equal to or greater than "0" and equal to or less
than 1. In the first implementation, the value of x of YPV is equal to or
greater than 0.3 and equal to or less than 0.8.

[0043] The inventors of the instant application examined light emitting
characteristics under ultraviolet excitation, especially afterglow
characteristics, and PDP characteristics with respect to the YPV having
different values of x as Eu3+ activated-red phosphor material. As a
result, in a specific combination range, it was discovered that the value
of x achieved high luminance, appropriate color purity, and a short
afterglow time of 4.0 msec or less. Red light may be allowed even in the
afterglow time which is relatively longer than that of green light having
a long afterglow time, as image quality characteristics of a stereoscopic
image display apparatus. Therefore, it is allowable that the afterglow
time be 4.0 msec or less. It is preferable that the afterglow time be 3.5
msec or less, especially, 3.0 msec or less. The technology that has been
disclosed here is based on the above described experiments.

[0044] Next, a manufacturing method of YPV according to the first
implementation will be described. Yttrium oxide (Y2O3),
diammonium hydrogen phosphate ((NH4)2HPO4), vanadium oxide
(V2O5), and europium oxide (Eu2O3) are weighed to
match a combination of a desired phosphor material. These are mixed, and
thereby a mixture is prepared. The mixture is baked at 1,100° C.
in the air. As a result, the red phosphor material is prepared. Here, the
value of x is determined by the molar ratio of diammonium hydrogen
phosphate ((NH4)2HPO4) and vanadium oxide
(V2O5). It should be noted that the above method describes an
exemplary method for manufacturing the YPV and other manufacturing
methods of the YPV are possible.

[0045] 3-4. Afterglow Time of Red Phosphor Material

[0046] The YPV according to the first implementation is an Eu3+
activated-red phosphor material. The YPV has a main light-emitting peak
in a wavelength range of equal to or greater than 610 nm and less than
630 nm. Further, the YPV emits red light in which a maximum intensity of
an orange emission component in a wavelength range of equal to or greater
than 580 nm and less than 600 nm is equal to or greater than 2% and less
than 20% of the main light-emission peak.

[0047] As for the emitting red light from the above described red phosphor
material, it is preferable that the maximum intensity of the orange
emission component on the same region is less than 20% of the main
light-emitting peak in the same region. More preferably, the maximum
intensity thereof is less than 15%, and further more preferably less than
13%. The Eu3+ activated-red phosphor material having the main
light-emitting peak in the same region is different from (Y,
Gd)BO3:Eu3+ and the like having the main light-emitting peak in
the vicinity of 590 nm. The red phosphor material has a large
light-emitting component ratio based on electronic dipole transition of
Eu3+ ion. Therefore, the red phosphor material emits red light of a
relatively short afterglow of about 2 msec to 5 msec. The above described
red light has a small orange light-emitting component ratio of a long
afterglow of about 10 msec or greater based on magnetic dipole transition
of Eu3+ ion. In addition, a red light-emitting component ratio of a
short afterglow of about 2 msec to 5 msec is large based on the
electronic dipole transition. Accordingly, it is preferable that the red
light having short afterglow characteristics of about 4.0 msec or less be
obtained.

[0048] Hereinafter, an afterglow time of YPV according to the first
implementation will be described.

[0049]FIG. 4 is a view showing the relationship between a value of x of
YPV according to a first implementation and an afterglow time of a plasma
display apparatus. In the first implementation, afterglow characteristics
of the plasma display apparatus using YPV when the value of x is 0, 0.1,
0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1 have been verified. As
shown in FIG. 4, it has been found that the afterglow time was increased
along with an increase in the value of x, and the afterglow time was
reduced along with a reduction in the value of x. It is preferable that
the afterglow time of the red light according to the first implementation
be equal to or less than 4.0 msec. Therefore, it has been found that the
value of x of YPV was preferably equal to or less than 0.8. It has been
found that the value of x may be equal to less than 0.7 to enable the
afterglow time to be equal to or less than 3.5 msec. Further, the value
of x is equal to or less than 0.6 to enable the afterglow time to be
equal to or less than 3.0 msec.

[0050] As for the above described afterglow characteristics, in the plasma
display apparatus according to the first implementation, when the value
of x of YPV is equal to or less than 0.8, the afterglow time may be equal
to or less than 4.0 msec. In addition, when the value of x of YPV is
equal to or less than 0.6 in the plasma display apparatus, the afterglow
time may be equal to or less than 3.0 msec.

[0051] 3-5. Powder Luminance of YPV and Luminance of Panel

[0052] FIG. 5 is a view showing the relationship between powder luminance
and a process maintenance rate with respect to a value of x of YPV
according to the first implementation. The powder luminance of YPV is
excited by an excimer lamp (a light source: krypton) having a wavelength
of 146 nm under a vacuum such that luminance is obtained, and the light
emission is measured and calculated using a spectrophotometer (C10027
manufactured by Hamamatsu Photonics). The YPV used here is formed by
pressuring at 4 MPa using a former of a fixture and a mold having a
predetermined opening area. A value of the powder luminance of YPV in
each value of x shown in FIG. 5 is a relative value.

[0053] When the value of x is 0.7, the value of powder luminance is set as
100%. The process maintenance rate is a maintenance rate of luminance
before and after the YPV passes through a manufacturing process of PDP.
The process maintenance rate is calculated as below. The paste containing
the phosphor material is coated on the rear plate 30 of the PDP, and a
peak intensity of 618 nm in a light emission spectrum obtained when
exciting the rear plate 30 having been baked, in the excimer lamp having
a wavelength of 146 nm under a vacuum, is set as 100%. As for the peak
intensity, the completed rear plate 30 of PDP 10 is cut out, and a value
of the peak intensity obtained from the rear plate 30 in the same manner
is relatively shown.

[0054] As shown in FIG. 5, it has been found that the powder luminance of
YPV was increased as x approaches from 0 to 0.7. Meanwhile, it has been
found that the powder luminance of YPV was reduced from the maximum value
when x exceeds 0.7. In other words, it has been found that the powder
luminance of YPV attains the maximum value when x is 0.7. In addition, it
has been found that the process maintenance rate was increased along with
an increase in the value of x. Meanwhile, it has been found that the
process maintenance rate was reduced along with a reduction in the value
of x. In particular, it has been found that the process maintenance rate
was rapidly increased when the value of x becomes larger than 0.8.
Meanwhile, it has been found that the process maintenance rate was
rapidly reduced when the value of x becomes less than 0.3.

[0055] Next, panel luminance of YPV will be described. FIG. 6 is a view
showing the relationship between a value of x of YPV and panel luminance
according to the first implementation. The panel luminance of YPV is
luminance obtained by measuring, using a luminance meter (CS-2000
manufactured by Konica Minolta), the quantity of light emission when only
the red phosphor layer in the plasma display apparatus is made to emit
light to thereby display a full screen as a red screen. A value of the
panel luminance of YPV in the value of x shown in FIG. 6 is a relative
value. When the value of x is 0.7, the value of the panel luminance is
set as 100%.

[0056] As shown in FIG. 6, it has been found that the panel luminance of
YPV was increased along with an increase in the value of x, and the panel
luminance attains the maximum value when the value of x is 0.7.
Meanwhile, it has been found that the panel luminance was significantly
reduced when the value of x of YPV becomes less than 0.3. From the
results of FIGS. 5 and 6, it has been found that the panel luminance had
the relationship between the powder luminance and the process maintenance
rate. Specifically, it has been found that, when multiplying a relative
value of the powder luminance by a relative value of the process
maintenance rate, the obtained value corresponded with a relative value
of the panel luminance shown in FIG. 6. As shown in FIG. 5, since both
the powder luminance and the process maintenance rate are increased as
the value of x approaches 0.7 from 0, a value of multiplying the powder
luminance by the process maintenance rate is also increased. In other
words, the panel luminance is increased as the value of x approaches 0.7.
Since the powder luminance when x is 0.7 attains the maximum value, the
panel luminance also attains the maximum value. Meanwhile, when the value
of x exceeds 0.7, the process maintenance rate is increased; however, the
powder luminance is reduced, so that a value of multiplying the powder
luminance by the process maintenance rate is reduced.

[0057] In other words, when the value of x exceeds 0.7, the panel
luminance is reduced, and attains a value lower than the maximum panel
luminance when the value of x is 0.7. In addition, when the value of x is
less than 0.3, the powder luminance is gradually reduced along with a
reduction in the value of x, and the process maintenance rate is rapidly
reduced. As a result, a value of multiplying the powder luminance by the
process maintenance rate is rapidly reduced. In other words, the panel
luminance shown in FIG. 6 is also rapidly reduced when the value of x is
less than 0.3.

[0058] Accordingly, it has been found that the relationship between the
powder luminance and the panel luminance was related to the process
maintenance rate, so that a value of multiplying the relative value of
the powder luminance by the relative value of the process maintenance
rate corresponded to the relative value of the panel luminance.

[0059] As described above, when considering the process maintenance rate,
when the value of x is equal to or greater than 0.3, process maintenance
of YPV is good even after the manufacturing process, and it is possible
to provide the high quality PDP apparatus having high panel luminance. In
addition, when considering the afterglow time, it is preferable that the
value of x be equal to or less than 0.8. It may be more preferable that
the value of x be equal to or less than 0.6. Therefore, it is preferable
that the value of x of YPV be equal to or greater than 0.3 and equal to
or less than 0.8.

[0060] Accordingly, it is possible to provide the plasma display apparatus
having good process maintenance rate and high luminance in the afterglow
time equal to or less than 4.0 msec. Specifically, when the value of x of
YPV is equal to or greater than 0.3 and equal to or less than 0.6, the
afterglow time is equal to or less than 3.0 msec. Furthermore, when the
value of x of YPV is equal to or greater than 0.6 and equal to or less
than 0.8, higher luminance may be maintained.

Second Implementation

[0061] Next, a second implementation will be described. For the sake of
brevity, descriptions of the same content as those of the first
implementation will be omitted.

[0062] 4-1. Red Phosphor Material

[0063] A plasma display apparatus according to a second implementation
includes a red phosphor layer 35R that is formed using a red phosphor
material containing YPV on which magnesium oxide (hereinafter, referred
to as MgO) is coated.

[0064] 4-2. Manufacturing Method of Red Phosphor Material

[0065] First, a method of coating a surface of YPV according to the first
implementation with MgO will be described. Magnesium nitrate (Mg
(NO3)2) was dissolved into water or an alkali aqueous solution
in a concentration of a predetermined amount. YPV (an average particle
diameter D50=3.6 μm) was fed into the dissolving solution to prepare a
mixture solution, and the mixture solution was further stirred.
Thereafter, the mixture solution was filtered, and then YPV remaining on
a filter paper was washed. Thereafter, YPV was dried at 150° C.
The dried YPV was baked at 400° C. to 800° C. under an air,
to prepare YPV with MgO coated on a surface thereof. The MgO may be
evenly coated on the surface of YPV to prevent the exposure of the
surface of YPV.

[0066] The above describes one method of coating the surface of YPV with
MgO; however, it should be noted that a method of coating the surface of
the YPV with MgO is not limited thereto and other methods are possible.

[0068] Next, a relationship between the panel luminance of the plasma
display apparatus including the red phosphor layer 35R that is formed
using the red phosphor material containing YPV with MgO coated thereon
will be described. FIG. 7 is a view showing the relationship between a
coated amount of MgO of YPV and panel luminance. Here, the panel
luminance of YPV when x=0.3, x=0.6, and x=0.8 are satisfied was measured.
The panel luminance in each value of x is shown as a relative value when
panel luminance of YPV on which MgO is not coated is set as 100%. In
addition, here, the coated amount of MgO shows a weight ratio of YPV to
MgO in the mixture solution. This is because a coated amount of MgO, for
example, when MgO is 5 g relative to 100 g of YPV in the mixture solution
is approximated almost to 5 wt % in a weight ratio to YPV. The panel
luminance in each value of x was measured using YPV when the coated
amount of MgO is 0.5 wt %, 1.0 wt %, 2.5 wt %, 5.0 wt %, and 10.0 wt %.

[0069] As shown in FIG. 7, it has been found that, in each value of x, the
panel luminance was increased along with an increase in the coated amount
of MgO in comparison with the panel luminance in which the coated amount
of MgO was 0 wt %. Here, as for the panel luminance, it has been expected
that the panel luminance when the coated amount of MgO is 1 wt % attains
the maximum value. This has been considered to be due to improvement of
the process maintenance rate by coating the surface of YPV with MgO. When
x is 0.3, the reason why the improvement of the panel luminance is the
largest in comparison with YPV on which MgO is not coated is because YPV
on which MgO is not coated when x is 0.3, has a lower process maintenance
rate in comparison with when the value of x is larger than 0.3, however,
has a large absolute value of luminance capable of being improved by
coating MgO. Meanwhile, when x is 0.8, the reason why the improvement of
the panel luminance is the smallest in comparison with YPV on which MgO
is not coated is because YPV on which MgO is not coated when x is 0.8 has
a higher process maintenance rate in comparison with when x is less than
0.8, and a small absolute value of luminance capable of being improved by
coating YPV with MgO.

[0070] In addition, it has been expected that, when the coated amount of
MgO is larger than 1 wt %, the panel luminance is gradually reduced. When
the coated amount of MgO is 5 wt %, the same panel luminance as that in
the case of YPV on which MgO is not coated is shown. Further, when the
coated amount of MgO exceeds 5 wt %, the panel luminance is smaller than
that in the case of YPV on which MgO is not coated. This has been
considered that the effect of a luminance reduction of a powder of YPV
due to the coating of MgO becomes large with respect to the fact that the
process maintenance rate is saturated along with an increase of the
coated amount of MgO.

[0071] To summarize the above, the second implementation describes a panel
having higher luminance than that of YPV on which MgO is not coated in a
range in which the coated amount of MgO is greater than 0 wt % and less
than 5 wt % may be obtained.

Third Implementation

[0072] Next, a third implementation will be described. For the sake of
brevity, descriptions of the same content as those of the first
implementation will be omitted.

[0073] 5-1. Red Phosphor Material

[0074] A plasma display apparatus according to a third implementation
includes a red phosphor layer 35R that is formed using a red phosphor
material containing YPV on which zinc oxide (hereinafter, referred to as
ZnO) is coated.

[0075] 5-2. Manufacturing Method of Red Phosphor Material

[0076] First, a method of coating a surface of YPV according to the first
implementation with ZnO will be described. Zinc nitrate
(Zn(NO3)2) was dissolved into water or an alkali aqueous
solution in a concentration of a predetermined amount. YPV (an average
particle diameter D50=3.6 μm) was fed into the dissolving solution to
prepare a mixture solution, and the mixture solution was further stirred.
Thereafter, the mixture solution was filtered, and then YPV remaining on
a filter paper was washed. Thereafter, YPV was dried at 150° C.
The dried YPV was baked at 400° C. to 800° C. under an air,
so that YPV with ZnO coated on a surface thereof was manufactured. The
ZnO may be evenly coated on the surface of YPV to prevent the exposure of
the surface of YPV.

[0077] The above describes one method of coating the surface of YPV with
ZnO; however, it should be noted that a method of coating the surface of
the YPV with ZnO is not limited thereto and other methods are possible.

[0079] Next, a relationship between the panel luminance of the plasma
display apparatus including the red phosphor layer 35R that is formed
using the red phosphor material containing YPV with ZnO coated thereon
will be described. FIG. 8 is a view showing the relationship between a
coated amount of ZnO in YPV and panel luminance. Here, the panel
luminance of YPV when x=0.3, x=0.6, and x=0.8 are satisfied was measured.
The panel luminance in each value of x is shown as a relative value when
panel luminance of YPV on which ZnO is not coated is set as 100%. In
addition, here, the coated amount of ZnO shows a weight ratio of YPV to
ZnO in the mixture solution. This is because a coated amount of ZnO, for
example, when ZnO is 5 g relative to 100 g of YPV in the mixture solution
is approximated almost to 5 wt % in a weight ratio to YPV. The panel
luminance in each value of x was measured using YPV when the coated
amount of ZnO is 0.5 wt %, 1.5 wt %, 3.0 wt %, 5.0 wt %, and 8.0 wt %.

[0080] As shown in FIG. 8, it has been found that, in each value of x, the
panel luminance was increased along with an increase in the coated amount
of ZnO in comparison with the panel luminance in which the coated amount
of ZnO was 0 wt %. Here, as for the panel luminance, it has been expected
that the panel luminance when the coated amount of ZnO is 1.5 wt %
attains the maximum value. This has been considered to be due to
improvement of the process maintenance rate by coating the surface of YPV
with ZnO. When x is 0.3, the reason why the improvement of the panel
luminance is the largest in comparison with YPV on which ZnO is not
coated is because YPV on which ZnO is not coated when x is 0.3, has a
lower process maintenance rate in comparison with when the value of x is
larger than 0.3, however, has a large absolute value of luminance capable
of being improved by coating ZnO. Meanwhile, when x is 0.8, the reason
why the improvement of the panel luminance is the smallest in comparison
with YPV on which ZnO is not coated is because YPV on which ZnO is not
coated when x is 0.8 has a higher process maintenance rate in comparison
with when x is less than 0.8, and a small absolute value of luminance
capable of being improved by coating YPV with ZnO.

[0081] In addition, it has been expected that, when the coated amount of
ZnO is larger than 1.5 wt %, the panel luminance is gradually reduced.
When the coated amount of ZnO is 5 wt %, the same panel luminance as that
in the case of YPV on which ZnO is not coated is shown. Further, when the
coated amount of ZnO exceeds 5 wt %, the panel luminance is smaller than
that in the case of YPV on which ZnO is not coated. This has been
considered that the effect of a luminance reduction of a powder of YPV
due to the coating of ZnO becomes large with respect to the fact that the
process maintenance rate is saturated along with an increase of the
coated amount of ZnO. In addition, in the exemplary implementation of the
above described YPV on which MgO is coated, the effect of an increase of
the panel luminance when the coated amount of ZnO is 1.5 wt % in YPV on
which ZnO is coated becomes the maximum with respect to the fact that the
effect of an increase of the panel luminance when the coated amount of
MgO is 1.0 wt %. This is because a crystal density of MgO is 3.58
g/cm3, whereas a crystal density of ZnO is 5.64 g/cm.3 To this
end, the crystal density of ZnO is 1.5 times the crystal density of MgO.
As a result, when the surface of YPV is coated in the same area as a
coated area by MgO, ZnO requires 1.5 times a mass of MgO.

[0082] To summarize the above, the third implementation describes a panel
having higher luminance than that of YPV on which ZnO is not coated in a
range in which the coated amount of ZnO is greater than 0 wt % and less
than 5 wt % may be obtained.

Fourth Implementation

[0083] Next, a fourth implementation will be described. For the sake of
brevity, the descriptions of the same content as those of the first
implementation will be omitted.

[0084] 6-1. Red Phosphor Material

[0085] A plasma display apparatus according to a fourth implementation
includes a red phosphor layer 35R that is formed using a red phosphor
material containing YPV on which silicon dioxide (hereinafter, referred
to as SiO2) is coated. In the fourth implementation, as the red
phosphor layer, YPV of x=0.7 (as the red phosphor material containing
Y(P0.7V0.3)O4:Eu in which the value of x is equal to or
less than 0.8) is used.

[0086] 6-2. Manufacturing Method of Red Phosphor Material

[0087] First, a method of coating the surface of YPV according to the
first implementation with SiO2 will be described. YPV (an average
particle diameter D50=3.6 μm) was fed into water to prepare a mixture
solution. The mixture solution was stirred to prepare a suspension of
YPV. Sodium silicate (Na2SiO3) of a predetermined amount was
added to the suspension. Acid such as hydrochloric acid (HCI) was
gradually added to the suspension while the suspension was maintained at
a high temperature of 70° C. or above. The suspension may be
neutral or have a mild acidity. Due to this, silica was evenly deposited
on the surface of YPV at high density. The suspension was filtered, and
YPV remaining on a filter paper was washed. Thereafter, YPV was dried at
150° C. The dried YPV was baked at 400° C. to 800°
C. under an air to prepare YPV with SiO2 coated on a surface
thereof. The SiO2 may be evenly coated on the surface of YPV to
prevent the exposure of the surface of YPV.

[0088] The above describes one method of coating the surface of YPV with
SiO2; however, it should be noted that a method of coating the
surface of the YPV with SiO2 is not limited thereto and other
methods are possible.

[0090] Next, powder luminance of YPV and a process luminance degradation
rate will be described. FIG. 9 is a view showing the relationship between
relative luminance and a luminance degradation rate with respect to a
coated amount of SiO2 of YPV. A bar graph shows the relationship
between a coated amount of SiO2 and relative luminance (%) in each
process which will be described later (a left vertical axis). A curved
line graph shows the relationship between the coated amount of SiO2
and a process luminance degradation rate (%) which is changed between
respective processes which will be described later (right vertical axis).
In addition, here, the coated amount of SiO2 shows a weight ratio of
YPV to SiO2 in the mixture solution. This is because a coated amount
of SiO2, for example, when SiO2 is 5 g relative to 100 g of YPV
in the mixture solution is approximated almost to 5 wt % in a weight
ratio to YPV.

[0091] The relative luminance in each process is defined as below. An
initial powder relative luminance before performing a phosphor baking
process corresponds to luminance of a phosphor powder before a phosphor
paste preparing process. The relative luminance after the process of
baking the phosphor corresponds to luminance of a phosphor after a
process of baking a phosphor paste in a panel production process. The
relative luminance after a vacuum baking process of the phosphor
corresponds to equivalent luminance to the phosphor after an airtight
sealing process in the panel production process. Further, the initial
powder luminance of YPV shown in FIG. 9 is defined as below. The initial
powder luminance is luminance obtained by exciting YPV formed by
pressuring at 4 MPa in the excimer lamp (a light source: krypton) having
a wavelength of 146 nm under a vacuum using a former of a fixture and a
mold having a predetermined opening area, and measuring and calculating
the light emission using a spectrophotometer (C10027 manufactured by
Hamamatsu Photonics). The relative luminance shown in FIG. 9 sets initial
powder luminance of a case in which SiO2 is not coated as 100%, and
relatively shows luminance of a phosphor in each coated amount.

[0092] The process luminance degradation rate that is changed between
respective processes is defined as below. A phosphor baking luminance
degradation rate shows the changing rate of the relative luminance before
and after the baking process of the phosphor. The vacuum baking luminance
degradation rate shows the changing rate of the relative luminance before
and after the vacuum baking process. The process luminance degradation
rate sets the relative luminance in the previous process as 100%. For
example, the phosphor baking luminance degradation rate shows the
changing rate (%) toward the relative luminance after the baking process
of the phosphor from the relative luminance of an initial powder. The
vacuum baking degradation rate shows the changing rate (%) toward the
relative luminance after the vacuum baking from the relative luminance
after the phosphor baking. The process luminance degradation rate
corresponds to 0% when the relative luminance before and after the
process is not changed, and shows a positive value when the luminance is
degraded. For example, the luminance degradation rate in the phosphor
baking process shows the changing rate toward the relative luminance
after the phosphor baking process from the initial powder relative
luminance. The degradation rate after the vacuum baking process shows the
changing rate toward the relative luminance after the vacuum baking from
the relative luminance after the phosphor baking.

[0093] 6-4. Experimental Results

[0094] From FIG. 9, a process luminance degradation rate of the phosphor
baking process and the vacuum baking process is reduced by coating YPV
with SiO2, and the relative luminance after the vacuum baking is
increased.

[0095] 6-4-1. Comparative Example

[0096] In the comparative example, the relative luminance of YPV on which
SiO2 is not coated and a luminance degradation rate are shown. With
respect to the fact that an initial powder relative luminance of YPV on
which SiO2 is not coated is 100%, luminance after the phosphor
baking process is 96.1%, resulting in 3.9% luminance degradation.
Further, by vacuum-baking YPV on which SiO2 is not coated, the
vacuum baking relative luminance is 73.7%, resulting in 23.4% luminance
degradation due to the vacuum-baking.

[0097] 6-4-2. Example 1

[0098] In the example 1, the relative luminance of YPV on which SiO2
is coated in an amount of 0.5 wt % and a luminance degradation rate are
shown. With respect to the fact that an initial powder relative luminance
of YPV on which SiO2 is coated in an amount of 0.5 wt % is 99.4%,
luminance after the phosphor baking process is 98.8% to obtain the
luminance degradation rate of 0.6%. Further, by vacuum-baking YPV, the
vacuum baking relative luminance is 79.4%, and luminance degradation of
19.4% occurs, so that luminance degradation suppression effect of 3.7% is
seen in comparison with the relative luminance after vacuum-baking YPV on
which SiO2 is not coated.

[0099] 6-4-3. Example 2

[0100] In the example 2, the relative luminance of YPV on which SiO2
is coated in an amount of 1.0 wt % and a luminance degradation rate are
shown. With respect to the fact that an initial powder relative luminance
of YPV on which SiO2 is coated in an amount of 1.0 wt % is 97.5%,
luminance after the phosphor baking process is 98.6% so that luminance
recovery of 1.1% is seen. Further, by vacuum-baking YPV, the vacuum
baking relative luminance is 79.0%, and luminance degradation of 19.6%
occurs, so that luminance degradation suppression effect of 3.5% is seen
in comparison with the relative luminance after vacuum-baking YPV on
which SiO2 is not coated.

[0101] 6-4-4. Example 3

[0102] In the example 3, the relative luminance of YPV on which SiO2
is coated in an amount of 2.0 wt % and a luminance degradation rate are
shown. With respect to the fact that an initial powder relative luminance
of YPV on which SiO2 is coated in an amount of 2.0 wt % is 99.5%,
luminance after the phosphor baking process is 98.6% so that luminance
degradation of 0.9% is seen. Further, by vacuum-baking YPV, the vacuum
baking relative luminance is 83.0%, and luminance degradation of 15.6%
occurs, so that luminance degradation suppression effect of 7.8% is seen
in comparison with the relative luminance after vacuum-baking YPV on
which SiO2 is not coated.

[0103] 6-5 Conclusion

[0104] YPV is coated with SiO2, so that the vacuum baking luminance
degradation rate of YPV is reduced. The relative luminance after the
vacuum baking process is also improved. Therefore, the luminance
degradation in the panel production process is suppressed, resulting in
improvement of panel luminance. In addition, even in YPV according to the
fourth implementation, YPV having the same average particle diameter is
used, so that the fourth implementation may have the same results as
those of the second and third implementations. In other words, similar to
the second and third implementations, when the coated amount of SiO2
exceeds 5 wt %, corresponding panel luminance becomes smaller than the
panel luminance of the case of YPV on which SiO2 is not coated. This
has been considered that the effect of a luminance reduction of a powder
of YPV due to the coating of SiO2 becomes large with respect to the
fact that the process maintenance rate is saturated along with an
increase in the coated amount of SiO2.

[0105] Accordingly, it is preferable that the coated amount of SiO2
be larger than 0 wt % and less than 5.0 wt %.

[0106] The red phosphor material may be excellent in red color purity by
changing the type or the composition of the phosphor, or the like.
However, the red phosphor material may have a problem in that luminance
is reduced when trying to obtain red light of short afterglow. The
technology disclosed herein solves the above described problems, and
provides a red phosphor material which reduces an afterglow time while
suppressing a reduction in luminance. In order to solve the above
problems, technology disclosed herein has the following features.

[0107] (1) The red phosphor material of the technology disclosed here
includes Y(Px, V1-x)O4:Eu (where, a value of x is equal to
or greater than 0.3 and equal to or less than 0.8). As a result, the red
phosphor material can reduce the afterglow time while suppressing a
reduction in luminance.

[0108] (2) As for the red phosphor material described in (1), it is
preferable that the value of x be equal to or greater than 0.3 and equal
to or less than 0.6. Due to this, it is possible to further suppress YPV
from being degraded in short afterglow and in the course of the baking
process.

[0109] (3) As for the red phosphor material described in (1), it is
preferable that the value of x be equal to or greater than 0.6 and equal
to or less than 0.8. Due to this, it is possible to provide the red
phosphor material having higher luminance in the afterglow time equal to
or less than 4.0 msec.

[0110] (4) As for the red phosphor material described in any one of (1) to
(3), it is preferable that a surface of Y(Px, V1-x)O4:Eu
is coated with at least one metal oxide selected from the group
consisting of magnesium oxide, zinc oxide, and silicon dioxide, and a
weight % concentration of the metal oxide with respect to Y(Px,
V1-x)O4:Eu is greater than 0 wt % and less than 5 wt %. Due to
this, it is possible to suppress YPV from being degraded in the course of
the baking process.

[0111] (5) In the PDP including the red phosphor layer, the red phosphor
layer is formed using the red phosphor material described in (1). Due to
this, it is possible to provide PDP which reduces the afterglow time
while suppressing the reduction of luminance.

[0112] (6) In the plasma display panel including the red phosphor layer,
it is preferable that the red phosphor layer be formed using the red
phosphor material described in any one of (2) and (3). Due to this, it is
possible to achieve a PDP having the short afterglow equal to or less
than 4.0 msec. Further, it is possible to provide a PDP which suppresses
the phosphor from being degraded in the short afterglow equal to or less
than 3.0 msec and in the course of the baking process. In addition, it is
possible to provide a PDP having high luminance during the afterglow time
equal to or less than 4.0 msec. As a result, it is possible to achieve
the high-quality plasma display apparatus which has high luminance and
suppresses crosstalk.

[0113] (7) In a PDP including the red phosphor layer, the red phosphor
layer is formed using the red phosphor material described in (4). Due to
this, it is possible to provide a PDP which further suppresses YPV from
being degraded in the course of the baking process.

[0114] One of ordinary skill in the art recognizes that the technology
disclosed herein is not limited to the above-described features. Other
implementations are contemplated. For example, in the second to fourth
implementations, the red phosphor in which the surface of Y(Px,
V1-x)O4:Eu is coated with MgO, ZnO, or SiO2 has been
described. However, the red phosphor may be coated with other materials
such as, for example, strontium carbonate (SrCO3), calcium carbonate
(CaCO3), barium carbonate (BaCO3), or diphosphorus pentoxide
(V2O5). In particular, when strontium carbonate (SrCO3) or
barium carbonate (BaCO3) is coated, the process maintenance rate may
be good.

[0115] The plasma display apparatus based on the teachings of the instant
application can have short afterglow characteristics and can enable high
luminance and high color gamut display. To this end, teachings of the
instant application can be useful in a high fineness image display
apparatus, a stereoscopic image display apparatus, and the like.